Uplink carrier selection for PRACH transmission between a NR dedicated carrier and a LTE/NR shared carrier

Abstract

A cellular communication system is disclosed in which user equipment (UE) initiates a random access channel (RACH) procedure by sending one or more messages, comprising a random access preamble, to a 5G base station, using one or more uplink carriers of a plurality of such carriers available for use by the UE. The base station selects an uplink carrier for initial access by the UE and informs the UE, as part of the RACH procedure, of the UL carrier selected by the base station.

The invention claimed is: 
     
       1. A method performed by a communication device configured with at least one uplink (UL) carrier, the method comprising:
 receiving, from a communication apparatus, a UL carrier indicator indicating which of a non-supplementary UL (non-SUL) carrier and a supplementary UL (SUL) carrier to use for a physical random access channel transmission; and 
 determining one UL carrier used for the physical random access channel transmission, based on the UL carrier indicator; 
 wherein: 
 the non-SUL carrier corresponds to an operating frequency band on a first Radio Access Technology (RAT), and 
 the SUL carrier corresponds to an operating frequency band on the first RAT and a second RAT. 
 
     
     
       2. The method according to  claim 1 , wherein the receiving the UL carrier indicator is before establishment of a connection to the communication apparatus is complete. 
     
     
       3. A method performed by a communication apparatus, the method comprising:
 sending, to a communication device configured with at least one uplink (UL) carrier, a UL carrier indicator indicating which of a non-supplementary UL (non-SUL) carrier and a supplementary UL (SUL) carrier to use for a physical random access channel transmission; 
 wherein: 
 the UL carrier indicator is used by the communication device to determine one UL carrier used for the physical random access channel transmission, 
 the non-SUL carrier corresponds to an operating frequency band on a first Radio Access Technology (RAT), and 
 the SUL carrier corresponds to an operating frequency band on the first RAT and a second RAT. 
 
     
     
       4. A communication device configured with at least one uplink (UL) carrier, the communication device comprising:
 a transceiver circuit; and 
 a controller, wherein the controller is configured to: 
 control the transceiver circuit to receive, from a communication apparatus, a UL carrier indicator indicating which of a non-supplementary UL (non-SUL) carrier and a supplementary UL (SUL) carrier to use for a physical random access channel transmission, and 
 determine one UL carrier used for the physical random access channel transmission, based on the UL carrier indicator; 
 wherein: 
 the non-SUL carrier corresponds to an operating frequency band on a first Radio Access Technology (RAT), and 
 the SUL carrier corresponds to an operating frequency band on the first RAT and a second RAT. 
 
     
     
       5. A communication apparatus comprising:
 a transceiver circuit; and 
 a controller, wherein the controller is configured to: 
 control the transceiver circuit to send, to a communication device configured with at least one uplink (UL) carrier, a UL carrier indicator indicating which of a non-supplementary UL (non-SUL) carrier and a supplementary UL (SUL) carrier to use for a physical random access channel transmission; 
 wherein: 
 the UL carrier indicator is used by the communication device to determine one UL carrier used for the physical random access channel transmission, 
 the non-SUL carrier corresponds to an operating frequency band on a first Radio Access Technology (RAT), and 
 the SUL carrier corresponds to an operating frequency band on the first RAT and a second RAT.